Compatibilized polyester/polyamide blends

ABSTRACT

Disclosed are compatibilized polymer blends comprising polyester, polyamide and a compatibilizer. Such compatibilized polymer blends, in preferred embodiments, are fabricated into monolayer or multilayer preforms and/or containers. Containers comprising such blends exhibit good gas barrier properties against gases such as oxygen and carbon dioxide, have a good appearance and may be used as containers for a wide variety of consumer products, including beverages, edibles and cosmetics. In multilayer containers comprising one or more layers of the compatibilized polymer blend and one or more layers of PET or PET-containing copolymers, the present containers have greatly improved impact delamination resistance as compared to those formed using uncompatibilized blends.

RELATED APPLICATION DATA

[0001] This application claims priority under 35 U.S.C. 119(e) fromprovisional application Ser. No. 60/366,701 filed Mar. 21, 2002, thedisclosure of which is incorporated in its entirety herein by reference.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention relates to compatibilized polymer blendscomprising polyester, polyamide and a compatibilizer. Suchcompatibilized polymer blends, in preferred embodiments, are fabricatedinto monolayer or multilayer preforms and/or containers.

[0004] 2. Description of the Related Art

[0005] Thermoplastic polyester containers as produced through stretchblow molding have various excellent properties including goodtransparency, good mechanical characteristics and good flavor barrierproperties, and are sanitary and safe for daily use. Therefore, theyhave many applications in various fields. However, since their gasbarrier properties are not always satisfactory, drinks, foods and othersin them could be stored only a relatively short period of time.

[0006] In order to achieve extended shelflife of PET containers byimproving barrier and mechanical properties, various methods ofcombining a thermoplastic polyester with a polyamide or Nylon barrierresin such as MXD6 with good gas barrier properties to give laminatedstructures have been proposed. Prior to stretch blowing, a preform(parison) is first formed. For forming the preform, various techniquese.g. coinjection molding, coextrusion molding, multi-stage, includingmultilayer, injection molding, etc. are employed. Of these, multilayerinjection molding is characterized by many as a suitable apparatus andmethod and the preforms produced through it would have a three or fivelayer structure in which each polyamide layer is sandwiched between PETlayers and therefore, even though the moldings have no adhesive resin(Ad) layer between the MXD6 layer and the PET layers they could besuitable multi-layered containers with seemingly good appearance atatmospheric pressures.

[0007] However, when such containers filled with drinks, foods andothers are shocked, for example, by dropping them, the PET layers andthe MXD6 layer are easily delaminated, thereby causing a serious problemwith appearance and performance of the containers. In that situation,coinjected molded containers having adhesive layers between eachpolyamide and PET layer have been proposed. Alternatively, the PETmultilayer container may be overdesigned by the incorporation of moreoverall weight in the preform/bottle to better resist delamination.

[0008] Such options have been investigated. However, the equipment forproducing them is often extremely complicated, and, in addition,controlling the thickness and/or positioning of each layer constitutingthem is often difficult. Therefore, those containers are inferior toothers having no adhesive layer in view of the production costs and theprocessability.

[0009] Other methods have also been investigated of blending MXD6 withany other resins for increasing the delamination resistance ofcontainers with no Ad layer. For example, in JP-A-1-176554 a method ofblending MXD6 with a polyamide-ester type thermoplastic resin, inJP-A-1-182023 a method of blending it with a metal-containing polyestertype thermoplastic resin, and in JP-A-3-175032 a method of blending itwith a thermoplastic polyurethane is disclosed. However, blending MXD6with such other resins in producing containers lowers the transparencyof the containers produced, and the containers will generally have anextremely bad appearance. In addition, the blending increases theproduction costs, and, depending on the type of the resins to beblended, there will occur still other problems in that the meltstability of the blends will be poor, acetaldehyde content will be high,and the barrier properties will be inadequate.

SUMMARY OF THE INVENTION

[0010] In accordance with preferred embodiments, there is provided acompatibilized polymer blend, comprising polyamide, PET or aPET-containing copolymer, and at least one compatibilizer. Preferredcompatibilizers include modified PET, including IPA modified PET,p-toluene sulfonic acid (pTSA) modified PET, pyrometillic dianhydride(PMDA) modified PET, and maleic anhydride modified PET; PET ionomers,including sulfonated PET, acrylic-modified polyolefin ionomer; andbisphenol-A epoxy resin, preferably of low molecular weight. In apreferred embodiment, a compatibilized polymer blend comprisespolyamide, preferably MXD-6, PET or a PET-containing copolymer, and atleast one compatibilizer selected from IPA-modified PET and PET ionomer.Although PET ionomers are preferred, other polyester ionomers such aspolybutylene terephthalate (PBT) ionomers and polypropylene (PPT)ionomers may also be used. In some embodiments, the compatibilizedpolymer blend can further comprise at least one antioxidant. In apreferred embodiment, the blend which forms a monolayer preform orcontainer or one layer of a preform or container comprises 15 mole % orless polyamide.

[0011] In a preferred embodiment, the compatibilized polymer blend isformed by a process comprising blending the polyamide, PET orPET-containing copolymer, and compatibilizer in the melt phase;extruding the blend into pellets; and heating said pellets, preferablyin an inert atmosphere, to a temperature between the blend's glasstransition temperature and melt temperature thereby causing solid statepolymerization and/or reactive compatibilization to occur. In someembodiments, the heating step may be omitted.

[0012] In accordance with preferred embodiments, a compatibilizedpolymer blend is used to form a monolayer or multilayer preform orcontainer. For example, one preferred preform or container is that whichcomprises a body and a neck finish, wherein at least said body comprisesat least a first layer comprising a compatibilized polymer blend, saidcompatibilized polymer blend comprising polyamide, PET or aPET-containing copolymer, and at least one compatibilizer, preferablyIPA-modified PET or PET ionomer. In a preferred embodiment, thepolyamide constitutes less than or equal to about 15 mol % of the blend.In accordance with another preferred embodiment, there is provided amultilayer preform or container, comprising a body portion and a neckfinish; wherein at least said body portion comprises at least one layercomprising a compatibilized polymer blend, said compatibilized polymerblend comprising polyamide, PET or a PET-containing copolymer, and atleast one compatibilizer, preferably IPA-modified PET or PET ionomer,and at least one layer comprising thermoplastic polyester, preferablyPET or PET-containing copolymer. The multilayer preform or container mayfurther comprise a third layer comprising a thermoplastic polyester,preferably PET or PET-containing copolymer.

[0013] In accordance with a preferred embodiment, there is provided apreform or container comprising a body portion and a neck finish,wherein at least said body portion comprises at least first and secondlayers, wherein said first layer comprises PET or a PET-containingcopolymer; and said second layer comprises a compatibilized polymerblend, said compatibilized polymer blend comprising polyamide, PET or aPET-containing copolymer, and at least one compatibilizer selected fromIPA-modified PET and PET ionomers.

[0014] Containers and preforms made from preferred compatibilizedpolymer blends exhibit lower haze as compared to those made fromnon-compatibilized blends. In multilayer containers and preforms, layersmade from compatibilized polymer blends according to preferredembodiments may also exhibit greater adhesion to PET than those madefrom non-compatibilized blends.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] Disclosed herein are compatibilized polyester/polyamide blendsand containers made therefrom with greatly improved impact delaminationresistance, adhesion, color, and clarity. In addition, these containerspreferably have one or more of the following properties: excellent gasbarrier properties against oxygen, carbon dioxide and other gasses,stable resin melts as well as improved appearance.

[0016] A preferred container is of the type used for beverages.Alternatively, embodiments of the container could take the form of jars,tubs, trays or bottles for holding edibles, cosmetics, and the like.Preferred containers may comprise a single layer or multiple layers. Aspresently contemplated, one embodiment of a container is formed from apreform comprising a body and a neck finish which is stretch blow moldedinto a container. However, for the sake of simplicity, these embodimentswill be described herein primarily as containers or preforms.

[0017] Furthermore, the containers described herein may be describedspecifically in relation to a particular component, polyethyleneterephthalate (PET), but preferred methods are applicable to many otherthermoplastics of the polyester type described herein. Other suitablepolyesters include, but are not limited to, polypropylene, polyethylene,polycarbonate, polyamides or acrylics.

[0018] In addition, preferred containers described herein may bedescribed specifically in relation to a particular component, MXD6 ornylon, but preferred methods are applicable to other polyamides, andsuch description should not be taken to exclude such other polyamides.

[0019] As used herein, the terms substantially or predominantlyindicates that the component described is present as 50% or more of thetotal content. PET is used to describe virgin and/or recycledpolyethylene terephthalate polymers, including virgin and/or recycledPET-containing copolymers. IPA modified PET is used to describe PETcomprising isophthalic acid (IPA).

[0020] In one embodiment, a container is a single layer comprising ablend of polyamide, polyester, and a compatibilizer. Other embodimentscomprise at least one layer of a blend of polyamide, polyester, and acompatibilizer and at least one layer comprising a thermoplasticpolyester. For example, a multi-layered container may be prepared byover-molding a polyester resin with apolyamide/polyesterterephthalate/compatibilizer resin mixture. In oneembodiment, a container may comprise a first layer of thermoplasticpolyester and a second layer comprising a blend of a polyamide, such asMXD6, and PET having an isophthalic acid content of from about 2 to 15mol % wherein the isophthalic acid acts as a compatibilizer. Further, ablend comprising polyamide/PET/compatibilizer, also referred to hereinas a compatibilized polymer blend, may also include an antioxidant toprevent haze and/or color formation inherent with polyamide/PET blends.As presently contemplated, one preferred, process for producing theselayers comprises an overmolding process as disclosed in U.S. Pat. No.6,352,426 B1 the disclosure of which is incorporated in its entiretyherein by reference. Further, these layers may also be produced by anysuitable process, including coinjection, injection molding with orwithout overmolding, and coextrusion.

A. Preferred Materials 1. Preferred Polyesters

[0021] Preferred thermoplastic polyesters include, but are not limitedto, condensed polymers that comprise an aromatic dicarboxylic acid orits alkyl ester and a diol. Suitable resins include a polyester resinincluding or consisting essentially of an ethylene terephthalatecomponent. In one embodiment, it is desirable that the total proportion(mol %) of terephthalic acid units and ethylene glycol unitsconstituting a preferred polyester is at least about 70 mol % relativeto the total moles of all constituent units that constitute saidpolyester, more preferably at least about 90 mol %. Such an embodimentis suitable for most applications, and is especially suitable for hotfill applications. If the total proportion of terephthalic acid unitsand ethylene glycol units constituting the preferred polyester issmaller than about 70 mol %, the copolyester will be amorphous. When hotfilled, stretched containers that comprise such an amorphous copolyesterare more susceptible to heat shrinkage, and may have poor heatresistance and lower strength.

[0022] A polyester resin, including, but not limited to those discussedabove, may be optionally copolymerized with any other bifunctionalcompound units except terephthalic acid units and ethylene glycol units,within the range not significantly interfering with the propertiesneeded or desired for the container or preform. In the embodimentdiscussed above, the proportion (mol %) of the additional units ispreferably at most about 30 mol % relative to the total moles of allconstituent units that constitute the polyester, more preferably at most20 mol %, even more preferably at most 10 mol %. Preferred bifunctionalcompound units that may be in the resin include dicarboxylic acid units,diol units and hydroxycarboxylic acid units. Other bifunctionalcompounds are also employable for the purpose, including, for example,aliphatic bifunctional compound units, alicyclic bifunctional compoundunits and aromatic bifunctional compound units.

[0023] Examples of preferred aliphatic bifunctional compound units,include, but are not limited to, divalent structure units to be derivedfrom aliphatic dicarboxylic acids and their ester-forming derivatives,such as malonic acid, succinic acid, adipic acid, azelaic acid andsebacic acid; from aliphatic hydroxycarboxylic acids and theirester-forming derivatives, such as 10-hydroxyoctadecanoic acid, lacticacid, hydroxyacrylic acid, 2-hydroxy-2-methylpropionic acid andhydroxybutyric acid, and from aliphatic diols such as trimethyleneglycol, tetramethylene glycol, hexamethylene glycol, neopentyl glycol,methylpentanediol and diethylene glycol. Neopentyl glycol units arepreferred aliphatic bifunctional compound units, since copolyesterscomprising the units do not lower the heat resistance of themulti-layered containers comprising them and are easy to produce.

[0024] Examples of alicyclic bifunctional compound units include, butare not limited to, divalent structure units to be derived fromalicyclic dicarboxylic acids and their ester-forming derivatives, suchas cyclohexanedicarboxylic acid, norbornenedicarboxylic acid andtricyclodecanedicarboxylic acid; alicyclic hydroxycarboxylic acids andtheir ester-forming derivatives such ashydroxymethylcyclohexane-carboxylic acid,hydroxymethylnorbornenecarboxylic acid andhydroxymethyltricyclodecanecarboxylic acid; and alicyclic diols such ascyclohexanedimethanol, norbornenedimethanol andtricyclodecanedimethanol. Cyclohexanedimethanol units orcyclohexanedicarboxylic acid units are preferred alicyclic bifunctionalcompound units, since copolyesters comprising them are easy to produce.Further, these units improve the drop-impact strength of the containersand greatly improve the transparency thereof.

[0025] The cyclohexanedimethanol unit as referred to herein is meant toindicate at least one divalent unit selected from1,2-cyclohexanedimethanol units, 1,3-cyclohexanedimethanol units and1,4-cyclohexanedimethanol units. The cyclohexanedicarboxylic acid unitalso referred to herein is to indicate at least one divalent unitselected from 1,2-cyclohexanedicarboxylic acid units,1,3-cyclohexanedicarboxylic acid units and 1,4-cyclohexanedicarboxylicacid units. Of the alicyclic bifunctional compound units noted above,more preferred are 1,4-cyclohexanedimethanol units and1,4-cyclohexanedicarboxylic acid units, since they are easily availableand since copolyesters comprising them and even moldings from suchcopolyesters could have higher drop-impact strength.

[0026] Preferred aromatic bifunctional compound units may be any ofaromatic dicarboxylic acid units, aromatic hydroxycarboxylic acid unitsand aromatic diol units. Examples include, but are not limited to,divalent units to be derived from aromatic dicarboxylic acids exceptterephthalic acid and their ester-forming derivatives, such asisophthalic acid (IPA), phthalic acid, biphenyldicarboxylic acid,diphenyl ether-dicarboxylic acid, diphenyl sulfone-dicarboxylic acid,diphenyl ketone-dicarboxylic acid, sodium sulfoisophthalate,2,6-naphthalenedicarboxylic acid, 1,4-naphthalenedicarboxylic acid and2,7-naphthalenedicarboxylic acid; aromatic hydroxycarboxylic acids andtheir ester-forming derivatives, such as hydroxybenzoic acid,hydroxytoluic acid, hydroxynaphthoic acid, 3-(hydroxyphenyl)propionicacid, hydroxyphenylacetic acid and 3-hydroxy-3-phenylpropionic acid, andaromatic diols such as bisphenol compounds and hydroquinone compounds.At least one of isophthalic acid units, phthalic acid units,naphthalenedicarboxylic acid units and 4,4′-biphenyldicarboxylic acidunits are preferred as the aromatic dicarboxylic acid units forbifunctional compound units, since copolyesters comprising them are easyto produce and since the monomer costs for them are low.

[0027] In particular, isophthalic acid (IPA) is advantageous in that themoldability of copolyesters comprising IPA is good. Further these IPAcopolyesters exhibit a broad range of molding conditions resulting ingood moldings and a low percentage of failed moldings. In addition, theacid is further advantageous in that it retards the crystallization rateof the copolyesters comprising it thereby preventing the whitening ofthe copolyester molding.

[0028] Naphthalenedicarboxylic acid is also advantageous in that itincreases the glass transition point of copolyesters comprising it andeven increases the heat resistance of containers comprising thecopolyesters. In addition, naphthalenedicarboxylic acid-copolymerizedpolyesters absorb UV rays, and are therefore preferably used inproducing containers that are desired to be resistant to UV rays. Forthe purpose of protecting the contents of containers from UV rays, it isdesirable that the thermoplastic polyester to be used for producing thecontainers has a naphthalenedicarboxylic acid component in an amount offrom 0.1 to 15 mol %, more preferably from 1.0 to 10 mol %, but alsoincluding about 0.5, 2, 3, 4, 5, 6, 7, 8, 9, 10.5 mol % relative to thesum total of all dicarboxylic acid components constituting it.2,6-naphthalenedicarboxylic acid component is preferred asnaphthalenedicarboxylic acid, since copolyesters comprising it are easyto produce and since the monomer cost for it is low.

[0029] Examples of suitable aromatic bifunctional compound unitsinclude, but are not limited to, diol units to be derived from2,2-bis(4-(2-hydroxyethoxy)phenyl)propane,2-(4-(2-(2-hydroxyethoxy)-ethoxy)phenyl)-2-(4-(2-hydroxyethoxy)phenyl)propane,2,2-bis(4-(2-(2-hydroxyethoxy)ethoxy)phenyl)propane,bis(4-(2-hydroxyethoxy)phenyl)sulfone,(4-((2-hydroxyethoxy)ethoxy)phenyl)-(4-(2-hydroxyethoxy)phenyl)sulfone,1,1-bis(4-(2-hydroxyethoxy)phenyl)cyclohexane,1-(4-(2-(2-hydroxyethoxy)ethoxy)ethoxy)phenyl)-1-(4-(2-hydroxyethoxy)phenyl)-cyclohexane,1,1-bis(4-(2-(2-hydroxyethoxy)ethoxy)phenyl)cyclohexane,2,2-bis(4-(2-hydroxyethoxy)-2,3,5,6-tetrabromophenyl)propane,1,4-bis(2-hydroxyethoxy)benzene,1-(2-hydroxyethoxy)-4-(2-(2-hydroxyethoxy)ethoxy)benzene or1,4-bis(2-(2-hydroxyethoxy)ethoxy)benzene. Of those diol units mentionedabove, preferred are 2,2-bis(4-(2-hydroxyethoxy)phenyl)propane units,bis(4-(2-hydroxyethoxy)phenyl)sulfone units and1,4-bis(2-hydroxyethoxy)benzene units, since polyester resins comprisingany of those diol units are easy to produce while having good meltstability. Further, moldings from such resins have good color tone andgood impact resistance.

[0030] Suitable polyester resins for the thermoplastic polyester layerof certain embodiments may have one or more bifunctional compound unitsincluding, but not limited to, those mentioned above. Resins containingsuch monomers in addition to terephthalic acid are referred to herein asPET-containing copolymers. Preferred polyester resins may contain asmall amount of diethylene glycol units from diethylene glycol, which isa dimer of an ethylene glycol component and is formed as a minorby-product in the process of producing the polyester resin. Because ofpotential problems involving factors such as glass transition point,heat resistance, mechanical strength and color tone of moldings such asbottles, it is preferred that the proportion of the diethylene glycolunits in the polyester resin be kept relatively low. Accordingly, in apreferred embodiment, the proportion of the diethylene glycol units inthe polyester resin is smaller than 3 mol %, including 1 and 2 mol %,relative to the total moles of all constituent units of the polyesterresin.

[0031] Polyester resins used in accordance with a preferred embodimentmay be optionally copolymerized with polyfunctional compound units,including, but not limited to, those preferably derived from at leastone polyfunctional compound having at least three groups selected fromcarboxyl groups, hydroxyl groups and their ester-forming groups. In oneembodiment, the proportion of the polyfunctional compound units in thepolyester resin are no more than 0.5 mol % relative to the total molesof all constituent units of the polyester. The polyfunctional compoundsfrom which the polyfunctional compound units are derived may be any ofpolyfunctional compounds, including, but not limited to those having atleast three carboxyl groups only, those having at least three hydroxylgroups only, and those having at least three carboxyl and hydroxylgroups in total. Suitable polyfunctional compound units, include, butare not limited to, those derived from aromatic polycarboxylic acidssuch as trimesic acid, trimellitic acid, 1,2,3-benzenetricarboxylicacid, pyromellitic acid and 1,4,5,8-naphthalenetetracarboxylic acid;aliphatic polycarboxylic acids such as 1,3,5-cyclohexanetricarboxylicacid; aromatic polyalcohols such as 1,3,5-trihydroxybenzene; aliphaticor alicyclic polyalcohols such as trimethylolpropane, pentaerythritol,glycerin and 1,3,5-cyclohexanetriol; aromatic hydroxycarboxylic acidssuch as 4-hydroxyisophthalic acid, 3-hydroxyisophthalic acid,2,3-dihydroxybenzoic acid, 2,4-dihydroxybenzoic acid,2,5-dihydroxybenzoic acid, 2,6-dihydroxybenzoic acid, protocatechuicacid, gallic acid and 2,4-dihydroxyphenylacetic acid; aliphatichydroxycarboxylic acids such as tartaric acid and malic acid; and theirester-forming derivatives.

[0032] A preferred polyester resin for the thermoplastic polyester layerof a preferred embodiment may comprise at least one polyfunctionalcompound unit such as, but not limited to, those mentioned above. Ofthose mentioned above, a preferred polyester resin preferably comprisesat least one polyfunctional compound unit to be derived from trimelliticacid, pyromellitic acid, trimesic acid, trimethylolpropane andpentaerythritol, in view of the ease of producing the polyesters and thecosts for their production. In addition, embodiments comprising suchpolyfunctional compound units may further comprise monofunctionalcompound units to be derived from at least one of monofunctionalcompounds such as, but not limited to, monocarboxylic acids,monoalcohols and their ester-forming derivatives. In embodimentsincluding such monofunctional compound units, it is desirable that theproportion of the monofunctional compound units is at most about 5 mol%, more preferably at most about 1%, but also including about 2, 3, and4%, relative to the total moles of all constituent units of the resin.Where the resin contains two or more different monofunctional compoundunits, the proportion indicates the total of all those units.Monofunctional compounds can be used to retard gellation when used atpreferred concentrations. This is because gelling of the resin thatsatisfies the requirement is retarded in many cases. If the proportionof the monofunctional compound units is larger than about 5 mol %, thepolymerization rate in producing the polyester resin, through melt orsolid-phase polymerization, may be low which further unfavorably lowersthe producibility of said polyester resin. In embodiments includingmonofunctional compound units, these units function as blocking compoundunits to block the terminal groups of the molecular chain or theterminal groups of the branched chains in the polyester resin, wherebythe polyester resin is prevented from being too crosslinked and frombeing gelled. Preferred monofunctional compound units are notspecifically defined, but preferably include, but are not limited to,those derived from at least one of monocarboxylic acids, monoalcoholsand their ester-forming derivatives. Suitable monofunctional compoundunits, include, but are not limited to, units derived frommonofunctional compounds, for example, aromatic monocarboxylic acidssuch as benzoic acid, o-methoxybenzoic acid, m-methoxybenzoic acid,p-methoxybenzoic acid, o-methylbenzoic acid, m-methylbenzoic acid,p-methylbenzoic acid, 2,3-dimethylbenzoic acid, 2,4-dimethylbenzoicacid, 2,5-dimethylbenzoic acid, 2,6-dimethylbenzoic acid,3,4-dimethylbenzoic acid, 3,5-dimethylbenzoic acid,2,4,6-trimethylbenzoic acid, 2,4,6-trimethoxybenzoic acid,3,4,5-trimethoxybenzoic acid, 1-naphthoic acid, 2-naphthoic acid,2-biphenylcarboxylic acid, 1-naphthalenacetic acid and naphthalenaceticacid; aliphatic monocarboxylic acids such as n-octanoic acid, n-nonanoicacid, myristic acid, pentadecanoic acid, stearic acid, oleic acid,linolic acid and linolenic acid; ester-forming derivatives of thosemonocarboxylic acids; aromatic alcohols such as benzyl alcohol,2,5-dimethylbenzyl alcohol, 2-phenethyl alcohol, phenol, 1-naphthol and2-naphthol; and aliphatic or alicyclic monoalcohols such as pentadecylalcohol, stearyl alcohol, polyethylene glycol monoalkyl ethers,polypropylene glycol monoalkyl ethers, polytetramethylene glycolmonoalkyl ethers, oleyl alcohol and cyclododecanol.

[0033] A preferred polyester resin may comprise at least onemonofunctional compound units such as, but not limited to, thosementioned above. Of the monofunctional compound units mentioned above,those to be derived from one or more monofunctional compounds selectedfrom benzoic acid, 2,4,6-trimethoxybenzoic acid, 2-naphthoic acid,stearic acid and stearyl alcohol are preferred for the polyesters foruse in accordance with preferred embodiments, in view of the ease inproducing the polyesters and of the costs for their production.

[0034] In view of its moldability, it is desirable that thethermoplastic polyester of a preferred embodiment comprises or consistsessentially of an ethylene terephthalate component, otherwise known aspolyethylene terephthalate or PET. The PET used in accordance withpreferred embodiments may be copolymerized with suitable amounts of oneor more comonomer components. It is desirable that thethus-copolymerized polyester resin contains a comonomer component in anamount of from 1 to 6 mol %, relative to the total moles of allconstituent units of the polyester, including about 1.5, 2, 2.5, 3, 3.5,4, 4.5, 5 and 5.5 mol %. In consideration of the degree ofcopolymerization with diethylene glycol that may be produced as aby-product in the process of producing the resin, some other comonomersmay be added to the resin so as to make the resin copolymerized withthem within the range noted above. Such other comonomers are notspecifically defined, for which any of the monomers mentioned above areusable. Some preferred monomers include, but are not limited to,neopentyl glycol, cyclohexanedimethanol (CHDM), cyclohexanedicarboxylicacid, isophthalic acid (IPA), and naphthalenedicarboxylic acid (NDC).

2. Preferred Polyamides

[0035] Preferred polyamides are preferably selected from the group ofpartially aromatic polyamides and can be formed from isophthalic acid,terephthalic acid, cyclohexanedicarboxylic acid, meta- or para-xylylenediamine, 1,3- or 1,4-cyclohexane(bis)methylamine, aliphatic diacids with6 to 12 carbon atoms, aliphatic amino acids or lactams with 6 to 12carbon atoms, aliphatic diamines with 4 to 12 carbon atoms, and othergenerally known polyamide forming diacids and diamines can be used.Preferred polyamides may also contain small amounts of trifunctional ortetrafunctional comonomers such as trimellitic anhydride, pyromelliticdianhydride, or other polyamide forming polyacids and polyamines knownin the art. Preferred partially aromatic polyamides include, but are notlimited to, poly(m-xylylene adipamide), poly(hexamethyleneisophthalamide), poly(hexamethylene adipamide-co-isophthalamide),poly(hexamethylene adipamide-co-terephthalamide), and poly(hexamethyleneisophthalamide-co-terephthalamide). One preferred partially aromaticpolyamide is poly(m-xylylene adipamide) having a number averagemolecular weight of 7,000 to 39,000, including 9,000, 11,000, 13,000,15,000, 17,000, 19,000, 21,000, 23,000, 25,000, 27,000, 29,000, 31,000,33,000, 35,000 and 37,000, and/or an inherent viscosity of 0.6 to 0.9dL/g, also including 0.65, 0.7, 0.75, 0.8, and 0.85 dL/g. Preferredaliphatic polyamides include, but are not limited to, poly(hexamethyleneadipamide) and poly(caprolactam). The most preferred low molecularweight aliphatic polyamide is poly(hexamethylene adipamide) having anumber average molecular weight of 13,000 to 16,000, but also including13,500, 14,000, 14,500, 15,000 and 15,500, and/or an inherent viscosityof 0.7 to 0.9 dL/g, but also including 0.75, 0.8, and 0.85 dL/g.

[0036] Aliphatic and partially aromatic polyamides of preferredembodiments used in conjunction with polyester, uniformly decrease theacetaldehyde concentration in articles formed from such blends.Partially aromatic polyamides, however, are preferred over the aliphaticpolyamides where clarity and dispersibility are crucial.

[0037] Polyamides are generally prepared by melt phase polymerizationfrom a diacid-diamine complex which may be prepared either in situ or ina separate step. In either method, the diacid and diamine are used asstarting materials. Alternatively, an ester form of the diacid may beused, preferably the dimethyl ester. If the ester is used, the reactionshould be carried out at a relatively low temperature, generally 80 to120° C., until the ester is converted to an amide. The mixture is thenheated to the polymerization temperature. In the case ofpolycaprolactam, either caprolactam or 6-aminocaproic acid can be usedas a starting material and the polymerization may be catalyzed by theaddition of adipic acid/hexamethylene diamine salt which results in anylon 6/66 copolymer. When the diacid-diamine complex is used, themixture is heated to melting and stirred until equilibration. Themolecular weight is controlled by the diacid-diamine ratio. An excess ofdiamine produces a higher concentration of terminal amino groups whichare available to react with acetaldehyde. If the diacid-diamine complexis prepared in a separate step, excess diamine is added prior to thepolymerization. The polymerization can be carried out either atatmospheric pressure or at elevated pressures.

[0038] As presently contemplated a preferred polyamide is MXD6 availablefrom Mitsubishi Gas Chemical (Japan).

3. Preferred Compatibilizers

[0039] Preferred compatibilizers include, but are not limited to,polyester ionomers, preferably PET ionomers, IPA modified PET, p-toluenesulfonic acid (pTSA) modified PET, pyrometillic dianhydride (PMDA)modified PET, and maleic anhydride modified PET. Other preferredcompatibilizers include acrylic modified polyolefin type ionomer and lowmolecular weight bisphenol-A epoxy resin-E44 which may be added directlyto a PET/polyamide blend. Further, trimellitic anhydride (TMA) may beadded to the polyamide, transesterified, mixed with PET and then coupledusing a bifunctional coupler such as, but not limited to,diphenylmethane-4,4-diisocyanate (MDI),diphenylmethane-4,4-diisopropylurethante (DU), or bisoxazoline (BOX).When compatibilizers are used, preferably one or more properties of thepolyamide/polyester blends are improved, such properties including,color, haze, and adhesion between a layer comprising a blend and a layercomprising polyester.

[0040] Preferred polyester ionomers include those disclosed in U.S. Pat.No. 6,500,895 B1, the disclosure of which is hereby incorporated byreference in its entirety. The ionomers disclosed therein compriserepeating units having the formula:

[0041] wherein R is hydrogen, halogen, alkyl having from one to abouttwenty carbons, or aryl having from one to about twenty carbons; M is ametal; n=1-5; R¹ is an alkylene radical having from one to about twelvecarbon atoms; A¹ is a 1,2-phenylene, 1,3-phenylene, or 1,4-phenyleneradical; and the mole fraction, x, of sulfonate-substituted units, isabout 0.1 to about 50 percent of the sum of x and y, with about 0.2 toabout 20 mole percent being preferred, about 0.5 to about 10 molepercent being more preferred, and about 1 to about 5 mole percent beingeven more preferred. Preferably R is hydrogen. Preferably R¹ is alkylenehaving from one to about six carbon atoms; more preferably R¹ isethylene or butylene. M is preferably an alkali or alkaline earth metal;M is more preferably sodium or potassium.

[0042] Preferred PET ionomers include sulfonated PET. A preferredsulfonated PET is Crystar® available from E.I. du Pont de Nemours andCompany, Wilmington, Del., USA. In embodiments comprising PET ionomers,they may be used in concentrations of about 0.01 weight % to about 15weight % of the total blend, preferably about 1 weight % to about 10weight %, also including about 2, 3, 4, 5, 6, 7, 8, 9, 11, 12, 13, and14 weight %. In other embodiments, other PET ionomer compatibilizers maybe used in similar quantities.

[0043] A preferred modified PET-type compatibilizer is IPA modified PET.In one embodiment, IPA modified PET preferably comprises from about 1mole % to about 6 mole % IPA of the total blend, including about 1.5, 2,2.5, 3, 3.5, 4, 4.5, 5 and 5.5 mol %. In other embodiments, modified PETcompatibilizers may be used in similar quantities.

[0044] Another preferred ionomer-type compatibilizer is a methacrylicacid modified olefinic ionomer. A preferred methacrylic acid modifiedolefinic ionomer is Surlyn® also available from E.I. du Pont de Nemoursand Company. In embodiments comprising methacrylic acid modifiedolefinic ionomers, they may be used in concentrations of about 0.01weight % to about 15 weight % of the total blend, preferably about 1weight % to about 10 weight %, also including about 2, 3, 4, 5, 6, 7, 8,9, 11, 12, 13, and 14 weight %. In other embodiments, othercompatibilizers may be used in similar quantities.

4. Preferred Performance Enhancing Additives

[0045] Many other ingredients can be added to the compositions ofpreferred embodiments to enhance the performance properties of preferredblends. For example, crystallization aids, impact modifiers, surfacelubricants, denesting agents, stabilizers, antioxidants, ultravioletlight absorbing agents, metal deactivators, colorants such as titaniumdioxide and carbon black, nucleating agents such as polyethylene andpolypropylene, phosphate stabilizers, fillers, and the like, can beincluded herein. Additives of these types and the use thereof are wellknown in the art and do not require extensive discussions. Therefore,only a limited number will be referred to, it being understood that anyof these compounds can be used so long as they do not interfere orhinder the present invention.

[0046] In applications where a clear, colorless resin is desired, theslight yellow color generated during processing can be masked byaddition of a blue dye. The colorant can be added to either component ofthe blend during polymerization or added directly to the blend duringcompounding. If added during blending, the colorant can be added eitherin pure form or as a concentrate. The amount of a colorant depends onits absorptivity and the desired color for the particular application. Apreferred colorant is1-cyano-6-(4-(2-hydroxyethyl)anilino)-3-methyl-3H-dibenzo(F,I,J)-isoquinoline-2,7-dioneused in an amount of from 2 to 15 ppm, but also including 3, 4, 5, 6, 7,8, 9, 10, 11, 12, 13, and 14 ppm.

[0047] Desirable additives also include impact modifiers andantioxidants. Examples of typical commercially available impactmodifiers well-known in the art and useful herein includeethylene/propylene terpolymers, styrene based block copolymers, andvarious acrylic core/shell type impact modifiers. The impact modifiersmay be used in conventional amounts from 0.1 to 25 weight percent of theoverall composition and preferably in amounts from 0.1 to 10, but alsoincluding, 1, 2, 3, 4, 5, 6, 7, 8, and 9, weight percent of thecomposition.

[0048] Examples of typical commercially available antioxidants usefulherein include, but are not limited to, hindered phenols, phosphites,diphosphites, polyphosphites, and mixtures thereof. Combinations ofaromatic and aliphatic phosphite compounds may also be included. IrgafosXP60 FF (Ciba Geigy) is a preferred antioxidant/processing aid tominimize haze and/or color formation normally associated withpolyamide/PET blends.

[0049] For improved gas barrier properties, nanocomposites may also beadded. These nanocomposites or nanoparticles are tiny particles ofmaterials which enhance the barrier properties of a material by creatinga more tortuous path for migrating oxygen or carbon dioxide. Onepreferred type of nanoparticular material is a microparticularclay-based product available from Southern Clay Products. Preferablythese are added to the polyamide prior to compatibilization of thepolyamide with the PET.

B. Preparation of the Polyamide, Polyester, Compatibilizer Blend

[0050] A preferred process for preparingpolyamide/polyester/compatibilizer blends according to preferredembodiments involves preparing the polyester, polyamide, andcompatibilizer respectively, by processes as mentioned previously. Thepolyester, polyamide, and compatibilizer are dried in an atmosphere ofdried air or dried nitrogen, or under reduced pressure. The polyester,polyamide, and compatibilizer are mixed and subsequently meltcompounded, for example, in a single or twin-screw extruder. Melttemperatures should be at least as high as the melting point of thepolyester and are typically in the range of 260-310° C. Preferably, themelt compounding temperature is maintained as low as possible withinsaid range. After completion of the melt compounding, the extrudate iswithdrawn in strand form, and recovered such as by cutting or pelleting.Instead of melt compounding, the polyester and polyamide may bedry-blended and over-molded or draw-formed into plastic articles orpreforms.

[0051] In a preferred embodiment, the pellets or cuttings prepared bymelt compounding described above then undergo solid state polymerization(SSP). A preferred SSP process comprises heating the pellets orcuttings, preferably under an inert atmosphere, thereby causing solidstate polymerization and/or reactive compatibilization to occur. SSPadvantageously increases the molecular weight and melt viscosity of theblend. Increased melt viscosity results in improved control of thelayers in multilayer injection processes. In addition, when SSP followsmelt compounding, the residence time for the mixing portion of the meltcompounding may be reduced as the compatibilization process continuesduring SSP. A preferred temperature for SSP is above the glasstransition point of the materials but below the melting point of thematerials, preferably above 100° C.

C. Preferred Containers

[0052] The blends of preferred embodiments serve as excellent startingmaterials for the production of moldings of all types. As presentlycontemplated, preferred embodiments may be monolayer or multilayercontainers produced by overmolding, such as by using the process notedsupra. Other embodiments may also be produced by other suitableprocesses such as coinjection or extrusion. Specific applicationsinclude various packaging applications such as thermoformed or injectionmolded trays, lids and cups; injection stretch blow-molded bottles, filmand sheet; extrusion blow-molded bottles and multilayer articles.Examples of package contents include, but are not limited to, food,beverages, and cosmetics.

[0053] PET blends with MXD6 are known in the industry and are utilizedfor oxygen and carbon dioxide barrier enhancement. Published literatureshows that improved oxygen barrier properties can be obtained withincreasing amounts of MXD6, but this increase also produces significanthaze formation.

[0054] MXD6 can be used as a blend in PET or as an inner layer in amultilayer container. These MXD6/PET containers will extend the shelflife of oxygen sensitive food products such as orange juice, tea, beer,etc. In addition, MXD6 can be used to reduce the carbon dioxidepermeability of the container or bottle to extend the shelf life ofcarbonated beverages.

[0055] Although barrier properties of PET bottles made with MXD6/PETblends will provide the desired shelf life, the associated haze and/orcolor problems preclude the general use of blends in the industry. Asthe amount of MXD6 increases the haze of blended bottles increasesdramatically as compared to multilayer bottles of the same or similarcompositions. The advantages of using a blend versus a multilayerstructure include the use of monolayer injection molding equipment andrelatively few concerns with delamination as with multilayer bottles.However, MXD6 use in the PET bottle industry is primarily withmultilayer technology due to clarity and recycling concerns. Thus thereis a need in the industry to develop a blend system of PET with MXD6that minimizes haze and/or color formation and allows for the use ofsimplified injection molding systems (monolayer or overmolding systems).In addition, blends are preferably compatible with recycle streams.

EXAMPLE 1

[0056] In this example two layer 0.5 liter bottles were made from 24gram overmolded preforms. The overmold resin content was 25% of thetotal weight of the preform/bottle. The inner layer was a standard PETbottle grade resin such as C93 resin from Dow Chemical. The followingblends were made and injected as the outer layer in these PET 2 layerpreforms; Blend % Haze in Bottle 6% MXD6 in PET   15% 6% MXD6 with IPAmodified PET (SKF)   7% 6% MXD6 with IPA modified PET (SKF) 5.75% and0.25% XP antioxidant from Ciba Geigy

[0057] Thus, the use of IPA modified PET, where IPA represents 2-5 mole% of the total blend content, achieved at least a 50% drop in the Haze.The use of an antioxidant/processing aid such as Irgafos XP furtherreduced the haze by 17.8% to produce a bottle with 62% less haze versusthe standard MXD6/PET blend. The presence of the antioxidant orstabilizer/processing aid is thought to prevent oxidation of the MXD6 atPET processing conditions. The IPA modified PET resin is believed tocompatibilize the MXD6 with the PET. This compatibilization also reduceshaze and/or color formation.

[0058] Another compatibilizer that can be used with the polyamide/PETblend is a PET ionomer comprising sulfonated PET.

[0059] In accordance with a preferred embodiment, the compatibilizedpolymer blend is used to form a monolayer preform or container such asby injection molding. Preferred monolayer preforms or containerscomprise a compatibilized polymer blend comprising a polyamide such asMXD6, PET or a PET-containing copolymer, and at least onecompatibilizer. In some embodiments, said compatibilized polymer blendfurther comprises an antioxidant. As discussed above, PET may includeone or more of the following: virgin PET, recycled PET, andpost-consumer PET. Suitable compatibilizers include one or more of thefollowing: PET ionomers, IPA modified PET, p-toluene sulfonic acid(pTSA) modified PET, pyrometillic dianhydride (PMDA) modified PET,maleic anhydride modified PET, acrylic-modified polyolefin ionomer, andbisphenol-A epoxy resin. Preferred compatibilizers comprise IPA modifiedPET and PET ionomers. In one embodiment, IPA modified PET comprises fromabout 1 mole % to about 6 mole % IPA of the total blend, also includingabout 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5 and 5.5 mole %. Preferred PETionomers comprise sulfonated PET. In some monolayer embodiments thecompatibilized polymer blend is disposed about the neck and body of thepreform or container while in other embodiments at least the body of thecontainer or preform comprises the compatibilized polymer blend.

[0060] In accordance with a preferred embodiment, the compatibilizedpolymer blend is used to form a multilayer preform or container such asby processes described above. Preferred multilayer preforms orcontainers comprise at least one layer of a compatibilized polymer blendcomprising a polyamide such as MXD6, PET or a PET-containing copolymer,and at least one compatibilizer and at least one layer of athermoplastic polyester, preferably as PET or a PET-containingcopolymer. In certain embodiments, the first layer of the container orpreform comprises the compatibilized polymer blend with the second layerof PET adhered directly to said first layer. In other embodiments, saidpreform or container comprises one or more compatibilized polymer blendlayers and one or more PET layers. In some embodiments, saidcompatibilized polymer blend further comprises an antioxidant. Suitablecompatibilizers include one or more of the following: PET ionomers, IPAmodified PET, p-toluene sulfonic acid (pTSA) modified PET, pyrometillicdianhydride (PMDA) modified PET, maleic anhydride modified PET,acrylic-modified polyolefin ionomer, and bisphenol-A epoxy resin.Preferred compatibilizers comprise IPA modified PET and PET ionomers. Inone embodiment, IPA modified PET comprises from about 1 mole % to about6 mole % IPA of the total blend, also including about 1.5, 2, 2.5, 3,3.5, 4, 4.5, 5 and 5.5 mole %. Preferred PET ionomers comprisesulfonated PET. Said thermoplastic layer may include one or more of thefollowing: virgin PET, recycled PET, and post-consumer PET. In somemultilayer embodiments the compatibilized polymer blend is disposedabout the neck and body of the preform or container while in otherembodiments at least the body of the container or preform comprises thecompatibilized polymer blend.

[0061] In accordance with some embodiments, concentrates of thecompatibilized polymer blends may be used. The use of concentratesallows for processing flexibility. Preferred concentrates may have amajority of either polyamide or PET or a PET-containing copolymer. Inone embodiment, concentrates can then be diluted with PET or PET recycleresin at desired quantities and injection molded as a monolayer ormultilayer structure with reduced haze and/or color. Preferably thefinal content of polyamide, such as MXD6, in the finished blendfollowing dilution is less than or equal to 15 mole % of the totalblend, but also including about 1, 3, 5, 7, 9, and 12 mole %, based oncost versus performance concerns. In other embodiments, the concentratesmay also be used without further dilution, such as by using coextrusionor coinjection, in applications where the polyamide/PET/compatibilizerlayer is sandwiched between other layers of the container.

[0062] For example, preferred MXD6/PET/compatibilizer blends where thePET contains IPA and/or a PET ionomer can be utilized via a concentrate.Exemplary concentrates include the following wherein the percentagesbelow refer to the percent of the total concentrate (which are not to betaken as limiting on the invention):

[0063] 80 weight % MXD6, 0.25-0.4 weight % Irgafos XP, and 19.75-19.60weight % IPA modified PET with an IPA range of 1.5-40 mole %

[0064] 80 weight % MXD6 with 20 weight % IPA polymer (100 mole % IPAcontent).

[0065] MXD6 with 0.1-10.0 weight % PET ionomer and PET copolymer with anIPA content of 1.5-40 mole %

[0066] MXD6 with 0.1-10.0 weight % PET ionomer

[0067] The percentages above should not be taken to limit the invention,for example where 1.5-40 mole % IPA is indicated, this also includes 5,10, 15, 20, 25, 30 and 35 mole % IPA. Further, 0.1-10.0 weight % PETionomer also includes, 1, 2, 3, 4, 5, 6, 7, 8, and 9 weight % PETionomer of the total concentrate. In other embodiments, concentrates mayhave higher percentages of polyamide and/or higher IPA both asconcentrates and when diluted.

[0068] In accordance with a preferred embodiment the concentrates areblended with polyester, preferably PET, so that the polyamideconcentration of the final blend used on the container is equal to orless than 15 mole % of the total blend, including about 1, 3, 5, 7, 9,and 12 mole %. In other embodiments utilizing concentrates, othercompatibilizers may be used in similar concentrations.

[0069] The concept of blending polyamides such as MXD6, withcompatibilizers such as PET ionomers or IPA, promotes compatibilizationleading to improved adhesion. For example, the blend of MXD6 with highIPA PET & Irgafos XP will allow the MXD6 to adhere to PET in coinjectionor coextrusion without impacting the performance of the MXD6.

[0070] In the case of overmolded preforms, such blends allow for betterrecycling and compatibility of the total container. When the concentrateis blended with PET prior to forming the bottle, thepolyamide/PET/compatibilizer blend content is diluted and thus becomesmore compatible with PET as compared to a straight blend of polyamideand PET. Another advantage of an overmolding process is that the blendcan be molded in the body of the preform and not in the neck finishwhere it is not needed, thus further reducing the amount of polyamide inthe recycling stream.

[0071] The various methods and techniques described above provide anumber of ways to carry out the invention. Of course, it is to beunderstood that not necessarily all objectives or advantages describedmay be achieved in accordance with any particular embodiment describedherein. Thus, for example, those skilled in the art will recognize thatthe apparatus may be made and the methods may be performed in a mannerthat achieves or optimizes one advantage or group of advantages astaught herein without necessarily achieving other objectives oradvantages as may be taught or suggested herein.

[0072] Furthermore, the skilled artisan will recognize theinterchangeability of various features from different embodiments.Similarly, the various features and steps discussed above, as well asother known equivalents for each such feature or step, can be mixed andmatched by one of ordinary skill in this art to perform methods inaccordance with principles described herein.

[0073] Although the invention has been disclosed in the context ofcertain embodiments and examples, it will be understood by those skilledin the art that the invention extends beyond the specifically disclosedembodiments to other alternative embodiments and/or uses and obviousmodifications and equivalents thereof. Accordingly, the invention is notintended to be limited by the specific disclosures of preferredembodiments herein, but instead by reference to claims attached hereto.

What is claimed is:
 1. A preform or container, comprising a body and aneck finish, wherein at least said body comprises at least a first layercomprising a compatibilized polymer blend, said compatibilized polymerblend comprising polyamide, PET or a PET-containing copolymer, and atleast one compatibilizer selected from IPA-modified PET and PETionomers.
 2. The preform or container of claim 1, wherein the containeror preform comprising compatibilized polymer blend exhibits lower hazethan a container or preform made from a non-compatibilized blend ofpolyamide and polyester.
 3. The preform or container of claim 1, whereinsaid preform is a monolayer preform and the neck finish comprises saidcompatibilized polymer blend.
 4. The preform or container of claim 1wherein said IPA modified PET comprises from about 1 mole % to 6 mole %IPA.
 5. The preform or container of claim 1, wherein said compatibilizeris a PET ionomer comprising sulfonated PET.
 6. The preform or containerof claim 1, wherein the PET or a PET-containing copolymer comprisesrecycled or post-consumer resin.
 7. The preform or container of claim 1wherein said at least one layer further comprises at least oneantioxidant.
 8. The preform or container of claim 1, wherein the PET ora PET-containing copolymer comprises recycled or post-consumer resin. 9.The preform or container of claim 1, further comprising a second layerdirectly adhered to the first layer, said second layer comprising PET ora PET-containing copolymer.
 10. The preform or container of claim 9,wherein the PET or a PET-containing copolymer of the first and/or secondlayers comprises recycled or post-consumer resin.
 11. The preform orcontainer of claim 1, wherein the polyamide constitutes less than orequal to about 15 mol % of the blend.
 12. A preform or container,comprising: a body portion and a neck finish, wherein at least said bodyportion comprises at least a first and second layers, wherein said firstlayer comprises a polyester; and said second layer comprises acompatibilized polymer blend, said compatibilized polymer blendcomprising: polyamide; PET or a PET-containing copolymer; and at leastone compatibilizer selected from IPA-modified PET and PET ionomers. 13.The preform or container of claim 12, wherein the container or preformcomprising compatibilized polymer blend exhibits lower haze than acontainer or preform made from a non-compatibilized blend of polyamideand polyester.
 14. The preform or container of claim 12, wherein saidPET or a PET-containing copolymer comprises recycled or post-consumermaterials.
 15. The preform or container of claim 12 wherein said IPAmodified PET comprises from about 1 mole % to 6 mole % IPA.
 16. Thepreform or container of claim 12, wherein said compatibilizer is a PETionomer comprising sulfonated PET.
 17. The preform or container of claim12 wherein said compatibilized polymer blend further comprises at leastone antioxidant.
 18. The preform or container of claim 12 wherein saidcompatibilized blend is substantially polyamide in content by mole %.19. The preform or container of claim 18 further comprising a thirdlayer comprising PET or PET-containing copolymer wherein the secondlayer comprising said compatibilized polymer blend lies between saidthird layer and said first layer.
 20. The preform or container of claim12 wherein said compatibilized blend is substantially PET orPET-containing copolymer in content by mole %.
 21. The preform orcontainer of claim 20 wherein said compatibilized polymer blendcomprises equal to or less than 15 mole % of the polyamide.
 22. Thepreform or container of claim 20 wherein said compatibilized polymerblend is made by a process in which a concentrate of the blend isdiluted with PET or PET-containing copolymer.
 23. The preform orcontainer of claim 12, wherein the preform or container has an interiorsurface and an exterior surface and the first layer forms the interiorsurface.
 24. The preform or container of claim 12 wherein saidcompatibilized polymer blend is made by a process in which a concentrateof the blend is diluted with PET or PET-containing copolymer.
 25. Acompatibilized polymer blend, comprising: a compatibilized blendcomprising polyamide, PET or a PET-containing copolymer, and at leastone compatibilizer, wherein the blend is formed by a process comprising:blending the polyamide, PET or PET-containing copolymer, andcompatibilizer in the melt phase; extruding the blend into pellets; andheating said pellets in an inert atmosphere to a temperature between theblend's glass transition temperature and melt temperature therebycausing solid state polymerization and/or reactive compatibilization tooccur.
 26. The compatibilized polymer blend of claim 25, wherein saidcompatibilizer is selected from IPA-modified PET and PET ionomers. 27.The compatibilized polymer blend of claim 25, wherein said IPA modifiedPET comprises from about 1 mole % to 6 mole % IPA.
 28. Thecompatibilized polymer blend of claim 25, wherein said compatibilizer isselected from IPA modified PET, p-toluene sulfonic acid (pTSA) modifiedPET, pyrometillic dianhydride (PMDA) modified PET, and maleic anhydridemodified PET.
 29. The compatibilized polymer blend of claim 25, whereinsaid compatibilizer is an acrylic-modified polyolefin ionomer or abisphenol-A epoxy resin.
 30. The compatibilized polymer blend of claim25, wherein said compatibilizer comprises a PET ionomer comprisingsulfonated PET.
 31. The compatibilized polymer blend of claim 25,wherein said blend further comprises at least one antioxidant.
 32. Acontainer or preform comprising a first layer comprising thecompatibilized polymer blend of claim
 25. 33. The container or preformof claim 32, wherein the first layer comprises no more than about 15mole % polyamide.
 34. The container or preform of claim 33, wherein thecompatibilizer comprises IPA-modified PET and PET ionomers.
 35. Thecontainer or preform of claim 33, wherein the container or preformcomprising compatibilized polymer blend exhibits lower haze than acontainer or preform made from a non-compatibilized blend of polyamideand polyester.
 36. The container or preform of claim 32, furthercomprising a second layer comprising polyester directly adhered to saidfirst layer.
 37. The container or preform of claim 36, wherein saidpolyester comprises PET or PET-containing copolymer.
 38. The containeror preform of claim 36, further comprising a third layer comprisingpolyester wherein said first layer is sandwiched between said second andthird layers and said first layer is substantially polyamide in contentby mole %.
 39. The container or preform of claim 38, wherein thepolyester of the second and/or third layer comprises PET orPET-containing copolymer.
 40. A compatibilized polymer blend, comprisingpolyamide; PET or a PET-containing copolymer; and at least onecompatibilizer selected from IPA-modified PET and PET ionomer; whereinthe polyamide constitutes less than or equal to about 15 mol % of theblend.
 41. The compatibilized polymer blend of claim 40, wherein saidcompatibilizer is IPA-modified PET which comprises from about 1 mole %to 6 mole % IPA.
 42. The compatibilized polymer blend of claim 40,wherein said compatibilizer is a PET ionomer comprising sulfonated PET.43. The compatibilized polymer blend of claim 40, wherein said blendfurther comprises at least one antioxidant.
 44. The compatibilizedpolymer blend of claim 40, wherein the blend forms at least a portion ofthe body of a container or preform.
 45. The preform or container ofclaim 44, wherein the container or preform comprising compatibilizedpolymer blend exhibits lower haze than a container or preform made froma non-compatibilized blend of polyamide and polyester.